There have been various devices proposed for producing a chorus effect in an electronic musical instrument, wherein the effect has been achieved by mixing a plurality of musical tone signals in which a slight difference of pitch has been caused to be present between each pair of adjacent signals. One type of such device does this by modulating the delay time of one or more musical tone signals.
In one prior art device for producing a chorus effect, wherein the delay time of the original musical tone signal is modulated by means of an electronic delay element as a bucket brigade device, and the modulated musical tone signal is mixed with the original non-modulated musical tone signal to produce a chorus effect, noise existing in the delay circuit, although it may be extremely small, often causes a jarring effect on the listener if it is modulated by a lower frequency wave so as to change the tone of the noise.